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Clarification on BTU needs calc. for my home

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Bster13, Dec 29, 2012.

  1. Bster13

    Bster13 Minister of Fire

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    So I've gone through the calculations (http://www.hearth.com/econtent/index.php/articles/how_much_heat_does_that_room_need) for each room here:
    https://docs.google.com/open?id=0BxjLmk_trl6BV3puM2h1SzFqcGs

    Video of my house floor plan:


    So I need a maximum of roughly 50k BTU/Hr at the coldest point of the year, to heat my entire 1974 sq. foot house in CT, seems reasonable. I assume this is an average over the span of 24 hrs. as less BTU/Hr. will be needed during the day, and more at night, correct?

    So in order to calc. the total # of BTUs I'd need to heat over the yearly heating season, I'd just multiply out the # of hours in the season by the 50k BTU/HR figure, and I'm good to go, correct?

    (I eventually want to calculate the payoff time for purchasing a wood stove/insert, so I need to nail down these details first).

    Thanks!

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  2. begreen

    begreen Mooderator Staff Member

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    Sheesh, engineers. :rolleyes: ::-) A few warmer or colder than normal winters and the ROI calcs could be out the window. While you are at it, calculate the heat loss of the house and the cost of directly addressing this heat loss. Then calculate the ROI on that investment including summer air conditioning load reduction.
    weatherguy and PapaDave like this.
  3. Shari

    Shari Minister of Fire

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    Without going thru all that you have computed, I figured it took us 3.5 oil fills (250 gal. roughly for each fill) per average heating season which equates 875 gallons/oil per season. With oil prices creeping up to $4 per gallon that would be $3500 per season.

    Our stove ran us right around $5,000 for stove/pipe/insulation/pro install plus a few items unique to our install.

    Less the then $1,500 federal tax credit = $3,500 cost for the switch from oil to wood heat.

    Year two = payoff year not including yearly wood processing costs (which is basically scoring free wood rounds/hauling wood home/splitting/etc.)

    The eight cords we started with this year was "free" wood but I've probably got, oh maybe, $200 in gas for the SUV/chainsaw/splitter invested. Eight cords should keep us in heat for 2-1/2 years at least and maybe longer ($100 +/- heating costs per year instead of $3,500 per year :)).

    We had the splitter & a chainsaw before the stove so I don't consider any cost for those in my figures. (We had a fireplace previously.)

    I did invest in a larger trailer - but that is also used for other things than just wood hauling. :)
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  4. Joful

    Joful Minister of Fire

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    Have you not been in the house long enough to have a history of what you've been paying for heat? If not, perhaps the previous owner can provide? That's much easier and far more accurate, than trying to extrapolate a very rough figure of BTU/day to an entire heating season.
    Backwoods Savage and PapaDave like this.
  5. jharkin

    jharkin Minister of Fire

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    +1

    Not to mention that multiplying the theoretical heat loss on the coldest day of the year times the number of days in winter is going to massively overestimate your usage.
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  6. PapaDave

    PapaDave Minister of Fire

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    Yep, much easier to use existing btu use, then transfer to wood use.
    Power co. may be able to provide prior use info. if you ask nice.:cool:
  7. Bster13

    Bster13 Minister of Fire

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    No prior info available, first winter in the new house.I will call the gas company and see if they'll be nice to me ("Hey, I am going to try and replace your service with a wood stove, what were the heating bills like last year?" :p)

    My payoff will be longer because I currently heat with Natural Gas and it's not crazy cold here. Was just trying to get a decent estimate. If it would take me 10+ years to make back the $, that would put some doubt in my head as the initial cost is going to be a couple grand for a professional install (Not willing to do it myself. I refinished ~1000 sq ft. of wood flooring before we moved in (new adventure for me) and I'm beat, :p For a Blaze King Princess Insert plus SS 6in liner (one story home) plus install, how much would u guys guess that'd be? (Keep in mind, I live in a high cost of living area, 1 hr north of NYC. doh!)

    Part of the "have my cake and eat it too" scenario here is the SO and I are constantly fighting with the thermostat. She wants it higher because she is cold, I want it lower to save $. It seemed like the stove w/ free collected firewood would be the answer provided the payoff time was decent.
  8. Bster13

    Bster13 Minister of Fire

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    If I came to ~50k BTU/Hr. for my single story, 1957 ranch in costal, lower CT...does that sound in the ballpark?
  9. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Sounds a bit high.

    Also you need to know that there can be a tremendous difference in how much wood you need. Different types of wood give off different amounts of heat. You also need to know that you need to store some wood and the sooner you get it the better off you will be. The most common mistake people make is to put in lots of time planning on the stove, the install and how many dollars spent and then expect everything to work perfectly after the install. As soon as the install is done or during the install, you go looking for the fuel. But wait!!!!! That fuel you will be getting is not in good condition for burning. You'll probably burn up to twice the amount of wood the first year plus you'll be spending extra for getting that dirty chimney cleaned. However, if you get your wood at least a year ahead of the time that you will need it, then you will be in much better shape......except if you buy or cut all oak. That oak definitely is one of the best woods for firewood. However, it also needs 2-3 times longer to dry before it can be burned. I do not mean to scare you but to make you aware that you need to spend as much time or even perhaps more in considering what you intend to do for the fuel. You can have a good experience burning wood or you can also have a miserable experience. Proper planning must include planning for the fuel you will burn. It is not like calling the oil man and having him fill the tank. Wood sellers will tell a good story about how their wood is good but you can find many, many stories where they were told the wood was ready to burn but it would not burn worth a hoot. And we also find that most new wood burners will blame everything on the stove and chimney but do not want to admit that their fuel is the problem. Be prepared.
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  10. Bster13

    Bster13 Minister of Fire

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    So I'm reading the max output for EPA ratings on stoves is not a real world example as stoves are capable of much higher output w/ cord wood (read this on Blaze King FAQ), so the Princess insert, or something similar fire box size should easily suit my needs if it is <50k BTU per hour when it is really cold out in CT.... it all comes down to how often I want to reload if I'm really cooking a small stove.

    What is weird though is the Woodstock Progress Hybrid Soapstone Stove is rated by the EPA for a max output of 73k BTU. That is far an away higher than the Blaze King Princess Stove (not insert) highest EPA output of 35600 BTU. According to Blaze King FAQ, the Princess stove (not insert) can go as high as 87,850 BTU. So if 29500 is to 87,850, then 73000 is to 217000 BTU on the Progress Hybrid? :eek:

    As for prepping wood supply, I will not buy an insert until next year as all my wood is green.
    And this is a thread I started to properly outfit myself for the wood collection process:
    http://www.arboristsite.com/firewood-heating-wood-burning-equipment/216216-8.htm

    I've called a local arborist and I hope to have free (green, hardwood) wood from him in the next week or so to further bulk up my supplies.

    Here is my pile today after processing a small amount I scored on Craigslist:
    photo (26).jpg
    Backwoods Savage likes this.
  11. madison

    madison Minister of Fire

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    IMHO, you are approaching this ass backwards. If you are considering an insert. You are going to be limited by the existing fireplace dimensions. Fit the largest thing you can into the box. And if you get too much "BTU's", she will be happy.
  12. Bster13

    Bster13 Minister of Fire

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    My fireplace will accommodate a BL Princess Insert, have not checked others. I am worried about overcooking us in the living room where we spend most of our time vs. trying to heat the entire house. I'd rather use up a bit of natural gas through out the rest of the house if that means keeping the temp reasonable in the living room where the insert will live (i.e. not too hot). Now as I learn more about CAT stoves, I figure most of them can be turned down low enough for that not to be a factor even with a large firebox.....
  13. Joful

    Joful Minister of Fire

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    You are correct, cat stoves (and in particular, Blaze Kings), excel at burning low. If you don't mind looking at it, you cannot beat BK on performance.

    Many here will tell you that BTU ratings are useless, which will be confusing to any engineer. The more accurate statement is that these ratings are collected under vastly varied conditions, and so are not very useful for comparing one stove to another. Some quote the EPA test rating, based on burning a fixed load of dimensional lumber. Others quote based on varying cord woods. The best quite both the EPA rating and the "max" cord wood expectation. Just keep in mind that your max burn time is at a much lower BTU/hr, and that your burn times at max BTU/hr will be disappointingly short.
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  14. Bster13

    Bster13 Minister of Fire

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  15. Joful

    Joful Minister of Fire

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    Yep... firebox size is what it's all about. Basically put, you're in control of the BTU/hr. by the fuel you load. There is no magic in one stove, versus another, with most stoves of one type (cat, non-cat, hybrid) being in the same ballpark as the rest. You control the fuel and how it's loaded, and therefore the BTU's and the rate at which they're released. Excepting the dynamics of cast iron vs. steel + firebrick vs. soapstone, all stoves of one technology are going to be roughly the same as others of the same firebox size. Decide on the max firebox size you can handle, which will usually be higher with a cat stove than a non-cat, and start shopping for stoves that meet that criteria. Manufacturer-claimed BTU ratings are too-often bogus.
  16. Bster13

    Bster13 Minister of Fire

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    High Valley 2500 insert looks very large...and cheaper than the BL Princess, hrmmm.... but no thermostatic control?
  17. Joful

    Joful Minister of Fire

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    BK, Sierra, High Valley, Appalacian... weren't you the guy with the aesthetically-picky fiancé, who didn't want to look at an insert? These are all decent heaters, but not exactly beauty queens. Have you checked Jotul, Lopi, Pacific Energy... ?
  18. Bster13

    Bster13 Minister of Fire

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    I have not considered cast irons stoves due to (perceived?) extra maintenance of inspecting and repairing cracks/seems.

    As for the fiancee... as she looks at mid-century modern dining sets, I've all but told her I'm going to get an insert and if she thinks they are all ugly, that's fine...I'll get the best functioning one for our needs. :)
  19. madison

    madison Minister of Fire

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    Just to save you some research time. Unless you are going to do this yourself (and willing to purchase via the internet). You are also going to be limited by the dealer(s) in your area and the products that they sell. If you are lucky enough to have multiple dealers, I would ask around at party's and/or work, who is reputable, and then go browsing. After feeling out what is available at the reputable dealer (and hopefully installer) start researching.

    If this is actually an insert, your options will be limited, by the size and construction of your existing fireplace. You may be lucky that a 1974 built home has a decent size fireplace vs a newer home with a zero clearance fireplace.

    Save the time spent on the calculations until you find out how many units will fit that are available by your best dealer.
  20. Bster13

    Bster13 Minister of Fire

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    There are a couple of dealers relatively close to me, one BK dealer as well....though does anyone know when BL will renegotiate their pricing with their East Coast distributor? I keep reading East Coast folks get nailed on pricing...

    My house is vintage 1957 and apparently has a good sized fireplace:

    http://www.hearth.com/talk/threads/...nswer-my-qs-please.101917/page-2#post-1311798

    photo (31).JPG

  21. begreen

    begreen Mooderator Staff Member

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    Most inserts are steel boxes, even those with cast iron facades.
  22. Bster13

    Bster13 Minister of Fire

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    Well then...learn something new about every minute on this forum (I have 15 brower tabs open on this forum alone, haha).

    So a stove could be full on cast iron, but "cast iron" inserts are generally steel boxes with a facade... is this due to cost? Ease of construction? I guess if it is mor eexpensive and more prone to cracking, no need to make the box out of cast iron if you'll never see it?

  23. begreen

    begreen Mooderator Staff Member

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    The notion that cast iron stoves are more prone to cracking is not correct in my experience. Cast iron is tough stuff, used for car headers, old potbelly stoves and the like. If the exterior casting is cracking it is most likely from user error or very long term use. Steel can crack or pop welds too from the same issues.

    A contemporary insert would look better here IMO. Something like the Heartstone Clydesdale, Osburn Matrix, would visually fit the style of the house better. A Blaze King Torino (gas insert) would also look pretty good there. But it sounds like you want engineering performance in a wood stove, so perhaps this whole discussion is somewhat moot? Get the BKP and tell her you got a stove named after her.
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  24. Backwoods Savage

    Backwoods Savage Minister of Fire

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    There should be no need of overcooking yourself in the living room. The neat little trick with a small desktop fan will also do wonders for heating the rest of the house. The little trick is to set a small desktop fan on the floor in a doorway or hallway and aim it toward the stove room. Use the lowest setting for the fan. Blowing that little bit of cooler air into the stove room will force the warm air out and will work with the natural convection. Cool air in on the lower level forces warm air out on the upper level and bingo! The further rooms warm up a lot. For ceiling fans, have the fan so it sucks air up rather than blowing air down.
  25. PapaDave

    PapaDave Minister of Fire

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    ^^^^ What he said. It works.

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